* {margin: 0;padding: 0;}
.box {
    width: 420px;
    height: 420px;
    border: 1px solid #ccc;
    position: relative;
}
.big{
    width: 420px;
    height: 420px;
    position: absolute;
    top: 0;
    left: 420px;
    border: 1px solid #ccc;
    overflow: hidden;
    display: none;
}
.mask{
    width: 175px;
    height: 175px;
    background: rgba(255, 255, 0, 0.4);
    position: absolute;
    top: 0;
    left: 0;
    cursor: move;
    display: none;
}
.small {
    position: relative;
}
.fdjzp{
    position: absolute;
    float: left;
    top: 397px;
    left: 398px;
}
.small:hover .fdjzp img{
    display: none;
}